On the Reflection of Cathode Rays. .'IS 7 



Table II. 



Reflector fixed at 90. 



Readings taken with the Faraday cylinder at different positions from 



95 to 45. 

 Pressure O00001 to O'OOOOlo atmosphere. 



First series Second series Mean 



Cylinder. deflection. deflection. deflection. 



95 0-3 0-2 0-25 



85 0-6 0-5 0-55 



75 1 1-1 1-05 



65 1-1 1-4 1-25 



55 1-4 1-6 1-5 



45 1-7 1-7 1-7 



with the cylinder in various positions. In all instances a maximum 

 deflection was obtained with positions that made the angles of incidence 

 and reflection approximately equal, and smaller and smaller deflections 

 resulted the further this position was departed from. However, as 

 more accurate readings were afterwards obtained with another tube 

 and more delicate arrangements, described below, it has been thought 

 best to omit detailed particulars of these observations. 



The above have, however, been mentioned to show that two tubes of 

 different descriptions gave similar results, and also that the galvano- 

 meter method of measuring the charge imparted to the Faraday cylin- 

 der, as described above, gave similar results as the quadrant electro- 

 meter used in the further experiments. 



The new tube with which experiments were next proceeded with is 

 shown in fig. 7. The arrangements for rotating the reflector in the 

 previous tube having been found somewhat unsatisfactory, in the new 

 tube both the reflector and the Faraday cylinder were attached to 

 ground stoppers, and furnished with pointers and scales, as in fig. 6, 

 so that the angles could be adjusted with great nicety. Further, in 

 order to obtain greater parallelism in the primary cathode stream, an 

 arrangement of cathode and anode was adopted similar to that used by 

 Professor J. J. Thomson.* According to this arrangement the cathode 

 rays from C are directed through two apertures about Ol inch diameter 

 in the hollow brass cylinder B, which is ground into a glass neck, and 

 by means of the terminal B' is used as anode. 



It being found that the employment of little electric power was con- 

 ducive to the maintenance of a constant vacuum, a 6-inch RuhmkorfF 

 coil was substituted for the larger one used previously, and as with the 

 diminished power, and with the very attenuated beam of cathode rays 



* ' The Discharge of Electricity through Grases,' by J. J. Thomson, pp. 152 and 

 164. 



